NEW YORK, NY, USA - For 59 minutes on Monday night, Serena Williams was nearly untouchable. 

In a highly anticipated US Open first-round clash, it was No.8 seed Serena who emerged victorious over longtime rival Maria Sharapova. The 23-time Grand Slam champion dominated from the start, and quickly added the 6-1, 6-1 rout to her head-to-head haul, extending her dominance over Sharapova to 20-2.

Read more: Serena subdues Sharapova in US Open first-round nightcap

“I just feel like her game really matches up well against mine,” Serena explained in her post-match press conference. “I always said her ball somehow lands in my strike zone. I don't know. It's just perfect for me.”

Understanding exactly how well Serena plays against Sharapova involves looking further than the 6-1, 6-1 number, or the even more daunting 20-2 number.

Serena Williams speaks after her first-round match against Maria Sharapova at the US Open. (Jimmie48 Photography/WTA)

Tonight, Serena had an answer for everything that Sharapova sent her way: she scored more than twice the winners (16 for Serena, six for Sharapova), made fewer unforced errors (12 to 20) and out-aced her opponent five to one. 

Even more impressively, Serena’s serve was not broken once, with the American saving all five break points faced in the second set. She also didn’t allow Sharapova any breathing room on her own serve: Serena won 100% of points off of the Russian’s second serves. 

Read more: 'It's never an easy road' - Sharapova plans smart schedule after Serena defeat at US Open

“I think I was able to zone in, especially down breakpoints, not letting her in the match because she's the kind of player that keeps going,” Serena said of her dominant performance. “Even towards the end, she just wants to keep fighting. One point here or there, she could have won at least another game. 

“I wanted to make sure I stayed focused.”

Serena celebrates after her first-round win. (Getty Images)

For Serena, who has not lost to Sharapova since 2004, it was nevertheless a tough opening round test after struggling with a back injury earlier in the summer. She was forced to retire due to painful back spasms in the final of the Rogers Cup in Toronto, trailing Andreescu 3-1, and then chose to skip Cincinnati in favor of more rest and training. 

She also shrugged off comments about the merits of the term ‘rivalry’, and acknowledged that the blockbuster opener might be exactly what she needed to get her US Open campaign off on the right foot. 

“It's really important because it's good to have tough matches,” Serena said. “Well, it's good to get through tough matches, especially for me. I really sometimes tend to start slow. It actually almost helps me.”

Up next, Serena Williams continues her US Open campaign in the second round against American wildcard Catherine McNally.